U.S. patent application number 12/527607 was filed with the patent office on 2010-05-13 for metal polishing slurry and polishing method.
This patent application is currently assigned to HITACHI CHEMICAL CO., LTD.. Invention is credited to Jin Amanokura, Sou Anzai, Shigeru Nobe, Takafumi Sakurada, Takashi Shinoda.
Application Number | 20100120250 12/527607 |
Document ID | / |
Family ID | 39721177 |
Filed Date | 2010-05-13 |
United States Patent
Application |
20100120250 |
Kind Code |
A1 |
Amanokura; Jin ; et
al. |
May 13, 2010 |
METAL POLISHING SLURRY AND POLISHING METHOD
Abstract
The present invention relates to a metal polishing slurry
containing abrasive grains, a metal-oxide-dissolving agent, and
water, wherein the abrasive grains contain two or more abrasive
grain species different from each other in average secondary
particle diameter. Using the metal polishing slurry of the present
invention, a metal polishing slurry can be obtained which gives a
large polishing rate of an interlayer dielectric layer, and is high
in the flatness of the polished surface. This metal polishing
slurry can provide suitable method for a semiconductor device which
is excellent in being made finer and thinner and in dimension
precision and in electric characteristics, is high in reliability,
and can attain a decrease in costs.
Inventors: |
Amanokura; Jin;
(Hitachi-shi, JP) ; Sakurada; Takafumi;
(Hitachi-shi, JP) ; Anzai; Sou; (Mito-shi, JP)
; Shinoda; Takashi; (Hitachi-shi, JP) ; Nobe;
Shigeru; (Hitachi-shi, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW, SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
HITACHI CHEMICAL CO., LTD.
Tokyo
JP
|
Family ID: |
39721177 |
Appl. No.: |
12/527607 |
Filed: |
February 22, 2008 |
PCT Filed: |
February 22, 2008 |
PCT NO: |
PCT/JP2008/053065 |
371 Date: |
August 18, 2009 |
Current U.S.
Class: |
438/693 ;
252/79.1; 252/79.2; 252/79.4; 257/E21.23 |
Current CPC
Class: |
C09K 3/1409 20130101;
C09K 3/1463 20130101; C09G 1/02 20130101; H01L 21/30625 20130101;
C23F 1/18 20130101; C23F 1/26 20130101; H01L 21/3212 20130101 |
Class at
Publication: |
438/693 ;
252/79.1; 252/79.2; 252/79.4; 257/E21.23 |
International
Class: |
H01L 21/302 20060101
H01L021/302; H01L 21/304 20060101 H01L021/304; H01L 21/306 20060101
H01L021/306; C09K 13/00 20060101 C09K013/00; C09K 13/04 20060101
C09K013/04; C09K 13/06 20060101 C09K013/06 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 27, 2007 |
JP |
2007-047007 |
May 10, 2007 |
JP |
2007-125840 |
Claims
1. A metal polishing slurry containing abrasive grains, a
metal-oxide-dissolving agent, and water, wherein the abrasive
grains contain two or more abrasive grain species different from
each other in average secondary particle diameter.
2. The metal polishing slurry according to claim 1, wherein the
average secondary particle diameter of the abrasive grains is in
the range of 1 to 1000 nm.
3. The metal polishing slurry according to claim 1, wherein the
abrasive grains contain first abrasive grains having an average
secondary particle diameter being in the range of 5 to 39 nm, and
second abrasive grains having an average secondary particle
diameter being in the range of 40 to 300 nm.
4. The metal polishing slurry according to claim 1, wherein the
abrasive grains contain abrasive grains having an average primary
particle diameter being in the range of 2 to 100 nm.
5. The metal polishing slurry according to claim 1, wherein a pH is
in the range of 2 to 5.
6. The metal polishing slurry according to claim 1, wherein the
abrasive grains are made of at least one selected from silica,
alumina, ceria, titania, zirconia and germania.
7. The metal polishing slurry according to claim 1, wherein the
metal-oxide-dissolving agent is at least one selected from organic
acids, organic-acid esters, ammonium salts of organic acids, and
inorganic acids.
8. The metal polishing slurry according to claim 1, which further
comprises a metal oxidizing agent.
9. The metal polishing slurry according to claim 8, wherein the
metal oxidizing agent is at least one selected from hydrogen
peroxide, nitric acid, potassium periodate, hypochlorous acid, and
ozone water.
10. The metal polishing slurry according to claim 1, which further
comprises a metal anticorrosive agent.
11. The metal polishing slurry according to claim 1, which further
comprises an organic solvent.
12. The metal polishing slurry according to claim 11, wherein the
organic solvent is at least one selected from glycol ether
compounds, alcohol compounds, and carbonate compounds.
13. The metal polishing slurry according to claim 1, which further
comprises a polymer having a weight-average molecular weight of 500
or more.
14. The metal polishing slurry according to claim 1, wherein a
polishing-receiving film to be polished with the metal polishing
slurry is a polishing-receiving film containing an
electroconductive material layer and a metal barrier layer.
15. The metal polishing slurry according to claim 1, wherein a
polishing-receiving film to be polished with the metal polishing
slurry is a polishing-receiving film containing an
electroconductive material layer and an interlayer dielectric
layer.
16. The metal polishing slurry according to claim 1, wherein a
polishing-receiving film to be polished with the metal polishing
slurry is a polishing-receiving film containing a metal barrier
layer and an interlayer dielectric layer.
17. The metal polishing slurry according to claim 1, wherein a
polishing-receiving film to be polished with the metal polishing
slurry is a polishing-receiving film containing an
electroconductive material layer, a metal barrier layer and an
interlayer dielectric layer.
18. The metal polishing slurry according to claim 14, wherein the
electroconductive material layer is a layer comprising at least one
selected from copper, copper alloys, copper oxides, and copper
alloy oxides.
19. The metal polishing slurry according to claim 14, wherein the
metal barrier layer is a single layer or a lamination made of two
or more layers, and the layer(s) (each) comprise(s) at least one
selected from tantalum, tantalum compounds, titanium, titanium
compounds, tungsten, tungsten compounds, ruthenium, ruthenium
compounds, copper-manganese alloys, and copper-manganese-silicon
oxide alloys.
20. The metal polishing slurry according to claim 15, wherein the
interlayer dielectric layer is a silicon-coating film or an organic
polymer film.
21. The metal polishing slurry according to claim 1, wherein the
amount of the abrasive grains is from 0.001 to 50 parts by mass,
based on 100 parts by mass of the whole of the metal polishing
slurry.
22. The metal polishing slurry according to claim 15, wherein the
ratio between the polishing rate of the electroconductive material
layer and that of the interlayer dielectric layer is 0.72 or
less.
23. A polishing method, comprising the step of polishing a
polishing-receiving film while supplying the metal polishing slurry
according to claim 1, onto a polishing cloth of a polishing table
by moving the polishing table and a substrate having the
polishing-receiving film relatively to each other in the state that
the substrate is pushed and pressed onto the polishing cloth.
24. The metal polishing slurry according to claim 15, wherein the
electroconductive material layer is a layer comprising at least one
selected from copper, copper alloys, copper oxides, and copper
alloy oxides.
25. The metal polishing slurry according to claim 17, wherein the
electroconductive material layer is a layer comprising at least one
selected from copper, copper alloys, copper oxides, and copper
alloy oxides.
26. The metal polishing slurry according to claim 16, wherein the
metal barrier layer is a single layer or a lamination made of two
or more layers, and the layer(s) (each) comprise(s) at least one
selected from tantalum, tantalum compounds, titanium, titanium
compounds, tungsten, tungsten compounds, ruthenium, ruthenium
compounds, copper-manganese alloys, and copper-manganese-silicon
oxide alloys.
27. The metal polishing slurry according to claim 17, wherein the
metal barrier layer is a single layer or a lamination made of two
or more layers, and the layer(s) (each) comprise(s) at least one
selected from tantalum, tantalum compounds, titanium, titanium
compounds, tungsten, tungsten compounds, ruthenium, ruthenium
compounds, copper-manganese alloys, and copper-manganese-silicon
oxide alloys.
28. The metal polishing slurry according to claim 16, wherein the
interlayer dielectric layer is a silicon-coating film or an organic
polymer film.
29. The metal polishing slurry according to claim 17, wherein the
interlayer dielectric layer is a silicon-coating film or an organic
polymer film.
Description
TECHNICAL FIELD
[0001] The present invention relates to a metal polishing slurry,
and a polishing method.
BACKGROUND ART
[0002] In recent years, new fine processing technologies have been
developed as the integration degree of semiconductor integrated
circuits (hereinafter referred to as LSIs) and the performance
thereof have been becoming high. Chemical mechanical polishing
(hereinafter referred to as CMP) is also one of the technologies,
and is a technique used frequently in the process of producing
LSIs, in particular, in the planarization of an interlayer
dielectric layer, the formation of metallic plugs, or the formation
of embedded interconnections in a multilayer interconnection
forming step. This technique is disclosed in, for example, the
specification of U.S. Pat. No. 4,944,836.
[0003] In order to make the performance of LSIs high, attempts of
making use of copper or copper alloy as an electroconductive
material which is to be a wiring material have been recently made.
However, copper or copper alloy is not easily subjected to fine
processing based on dry etching, which is frequently used to form
conventional aluminum alloy wiring. Thus, the so-called damascene
process is mainly adopted, which is a process of depositing a
copper or copper alloy thin film on an insulating film in which
grooves are beforehand made, so as to embed the film therein, and
then removing the thin film in any region other than the groove
regions by CMP to form embedded wiring. This technique is disclosed
in, for example, JP-A-2-278822.
[0004] An ordinary method of CMP for polishing a metal for wiring
regions, such as copper or copper alloy, is a method of causing a
polishing pad to attach onto a circular polishing table (platen),
impregnating the surface of the polishing pad with a metal
polishing slurry, pushing a metal-film-formed surface of a
substrate against it, and rotating the polishing table in the state
that a predetermined pressure (hereinafter referred to as a
polishing pressure) is applied thereto from the rear surface of the
polishing pad, thereby removing convex portions of the metallic
film by effect of mechanical friction between the polishing slurry
and the metallic film convex portions.
[0005] A metal polishing slurry used for CMP is generally composed
of an oxidizing agent, abrasive grains, and water. If necessary, a
metal-oxide-dissolving agent, a metal anticorrosive agent, and
others are added thereto. The surface of a metallic film is first
oxidized with the oxidizing agent to form an oxide layer, and the
oxide layer is ground away with the abrasive grains. This is
considered to be a basic mechanism. The oxide layer in concave
regions of the metallic film surface does not contact the polishing
pad very much; thus, the grinding-away effect of the abrasive
grains is not given thereto. Therefore, with the advance of CMP,
the metallic film convex regions are removed so that the substrate
surface is planarized. Details thereof are disclosed in Journal of
Electrochemical Society, Vol. 138, No. 11 (1991), 3460-3464.
[0006] It is mentioned that an effective method for making the
polishing rate of CMP high is the addition of a
metal-oxide-dissolving agent. This can be interpreted as follows:
when grains of a metal oxide ground away with the abrasive grains
are dissolved into the polishing slurry, the grinding-away effect
of the abrasive grains increases. The addition of the
metal-oxide-dissolving agent causes an improvement in the polishing
rate of CMP; however, when an oxide layer in concave regions of a
metallic film surface is also dissolved so that the metallic film
surface is made naked, the metallic film surface is further
oxidized with the oxidizer. When this is repeated, the dissolution
of the metallic film concave regions unfavorably advances. As a
result, there is generated a phenomenon that a central region of
the surface of metallic wiring embedded after the polishing is
depressed into a dish form (hereinafter, the phenomenon will be
referred to as "dishing"). Thus, the planarizing effect is
damaged.
[0007] In order to prevent this, a metal anticorrosive agent is
further added to the metal polishing slurry. The metal
anticorrosive agent is an agent for forming a protective film on
the oxide layer on the metallic film surface to prevent the oxide
layer from being etched.
[0008] This protective film can easily be ground away with the
abrasive grains. It is desired that the protective film does not
cause a fall in the polishing rate of CMP.
[0009] In order to restrain the dishing or etching of a metallic
film to form LSI wiring high in reliability, suggested is a method
using a metal polishing slurry containing a metal-oxide-dissolving
agent made of an aminoacetic acid, such as glycine, or
amidesulfuric acid, and benzotriazole as a metal anticorrosive
agent. This technique is described in, for example,
JP-A-8-83780.
[0010] Beneath a metal for wiring regions, such as copper or copper
alloy, a layer made of a conductor such as tantalum or a tantalum
compound is formed as a barrier layer in order to prevent the metal
from diffusing into the interlayer dielectric layer, or improve the
adhesive property of the metal onto the interlayer dielectric
layer. It is therefore necessary to make use of CMP to remove the
barrier layer naked in any region other than the wiring regions
into which the wiring region metal such as copper or copper alloy
is to be embedded. However, the conductor of the barrier layer is
higher in hardness than copper or copper alloy; therefore, a
combination of polishing materials for copper or copper alloy does
not give a sufficient polishing rate and further makes the flatness
and smoothness of the polished surface poor in many cases. Thus, a
two-stage polishing method is being investigated which is composed
of a first CMP polishing step for polishing the wiring region metal
such as copper or copper alloy, and a second CMP polishing step for
polishing the barrier layer.
[0011] The metal polishing slurry used in the second CMP polishing
step for polishing the barrier layer may be required to attain
ability to polish a silicon-coating film or an organic polymer
film, which is an interlayer dielectric layer in order to promote
the planarization of the polished surface. In order to improve the
polishing rate of the interlayer dielectric layer, suggested is a
method of enlarging the particle diameter of the abrasive grains
contained in the metal polishing slurry to perform polishing.
However, the method has a problem that scratches are generated in
the surface polished therewith, thereby causing electric
characteristic insufficiency. There is also caused a problem that
such electric characteristic insufficiency is generated by
insufficient washing after the CMP.
DISCLOSURE OF THE INVENTION
[0012] An object of the invention is to provide a metal polishing
slurry which gives a large polishing rate of an interlayer
dielectric layer, produces no scratches on a polished surface, and
makes the flatness and smoothness of the polished surface high.
Another object of the invention is to provide a polishing method
which is suitable for a highly reliable and low-cost semiconductor
device excellent in being made finer and thinner and in dimension
precision and electric characteristics, by using the metal
polishing slurry.
[0013] The invention relates to (1) a metal polishing slurry
containing abrasive grains, a metal-oxide-dissolving agent, and
water, wherein the abrasive grains contain two or more abrasive
grain species different from each other in average secondary
particle diameter.
[0014] The invention also relates to (2) the metal polishing slurry
according to item (1), wherein the average secondary particle
diameter of the abrasive grains is in the range of 1 to 1000
nm.
[0015] The invention also relates to (3) the metal polishing slurry
according to item (1), wherein the abrasive grains contain first
abrasive grains having an average secondary particle diameter being
in the range of 5 to 39 nm, and second abrasive grains having an
average secondary particle diameter being in the range of 40 to 300
nm.
[0016] The invention also relates to (4) the metal polishing slurry
according to item (1), wherein the abrasive grains contain abrasive
grains having an average primary particle diameter being in the
range of 2 to 100 nm.
[0017] The invention also relates to (5) the metal polishing slurry
according to any one of items (1) to (4), wherein a pH is in the
range of 2 to 5.
[0018] The invention also relates to (6) the metal polishing slurry
according to any one of items (1) to (5), wherein the abrasive
grains are made of at least one selected from silica, alumina,
ceria, titania, zirconia and germania.
[0019] The invention also relates to (7) the metal polishing slurry
according to any one of items (1) to (6), wherein the
metal-oxide-dissolving agent is at least one selected from organic
acids, organic-acid esters, ammonium salts of organic acids, and
inorganic acids.
[0020] The invention also relates to (8) the metal polishing slurry
according to any one of items (1) to (7), which further contains a
metal oxidizing agent.
[0021] The invention also relates to (9) the metal polishing slurry
according to item (8), wherein the metal oxidizing agent is at
least one selected from hydrogen peroxide, nitric acid, potassium
periodate, hypochlorous acid, and ozone water.
[0022] The invention also relates to (10) the metal polishing
slurry according to any one of items (1) to (9), which further
contains a metal anticorrosive agent.
[0023] The invention also relates to (11) the metal polishing
slurry according to any one of items (1) to (10), which further
contains an organic solvent.
[0024] The invention also relates to (12) the metal polishing
slurry according to item (11), wherein the organic solvent is at
least one selected from glycol ether compounds, alcohol compounds,
and carbonate compounds.
[0025] The invention also relates to (13) the metal polishing
slurry according to any one of items (1) to (12), which further
contains a polymer having a weight-average molecular weight of 500
or more.
[0026] The invention also relates to (14) the metal polishing
slurry according to any one of items (1) to (13), wherein a
polishing-receiving film to be polished with the metal polishing
slurry is a polishing-receiving film containing an
electroconductive material layer and a metal barrier layer.
[0027] The invention also relates to (15) the metal polishing
slurry according to any one of items (1) to (13), wherein a
polishing-receiving film to be polished with the metal polishing
slurry is a polishing-receiving film containing an
electroconductive material layer and an interlayer dielectric
layer.
[0028] The invention also relates to (16) the metal polishing
slurry according to any one of items (1) to (13), wherein a
polishing-receiving film to be polished with the metal polishing
slurry is a polishing-receiving film containing a metal barrier
layer and an interlayer dielectric layer.
[0029] The invention also relates to (17) the metal polishing
slurry according to any one of items (1) to (13), wherein a
polishing-receiving film to be polished with the metal polishing
slurry is a polishing-receiving film containing an
electroconductive material layer, a metal barrier layer and an
interlayer dielectric layer.
[0030] The invention also relates to (18) the metal polishing
slurry according to any one of item (14), (15) or (17), wherein the
electroconductive material layer is a layer containing at least one
selected from copper, copper alloys, copper oxides, and copper
alloy oxides.
[0031] The invention also relates to (19) the metal polishing
slurry according to any one of item (14), (16) or (17), wherein the
metal barrier layer is a single layer or a lamination made of two
or more layers, and the layer(s) contain(s) at least one selected
from tantalum, tantalum compounds, titanium, titanium compounds,
tungsten, tungsten compounds, ruthenium, ruthenium compounds,
copper-manganese alloys, and copper-manganese-silicon oxide
alloys.
[0032] The invention also relates to (20) the metal polishing
slurry according to any one of items (15) to (17), wherein the
interlayer dielectric layer is a silicon-coating film or an organic
polymer film.
[0033] The invention also relates to (21) the metal polishing
slurry according to any one of items (1) to (20), wherein the
amount of the abrasive grains is from 0.001 to 50 parts by mass,
based on 100 parts by mass of the whole of the metal polishing
slurry.
[0034] The invention also relates to (22) the metal polishing
slurry according to any one of items (15), and (17) to (21),
wherein the ratio between the polishing rate of the
electroconductive material layer and that of the interlayer
dielectric layer is 0.72 or less.
[0035] The invention also relates to (23) a polishing method,
comprising the step of polishing a polishing-receiving film while
supplying the metal polishing slurry according to any one of (1) to
(22), onto a polishing cloth of a polishing table by moving the
polishing table and a substrate having the polishing-receiving film
relatively to each other in the state that the substrate is pushed
and pressed onto the polishing cloth.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 are views referred to in order to describe polishing
steps wherein the metal polishing slurry of the invention is
used.
BEST MODE FOR CARRYING OUT THE INVENTION
[0037] A member to be polished in the invention is a patterned
substrate which has undergone a first CMP polishing step.
Specifically, the member is a desired patterned substrate obtained
by: preparing a substrate having an interlayer dielectric layer
having a surface composed of concave and convex regions, a metal
barrier layer which covers the interlayer dielectric layer along
its surface, and an electroconductive material layer which is
filled into the concave regions to cover the metal barrier layer;
and polishing the electroconductive material layer through a first
CMP polishing step, thereby making the metal barrier layer on the
convex regions naked, and causing the electroconductive material
layer in the concave regions to remain. The metal polishing slurry
of the invention is a slurry used in a second CMP polishing
step.
[0038] The metal polishing slurry of the invention contains
abrasive grains, a metal-oxide-dissolving agent, and water, wherein
the abrasive grains contain two or more abrasive grain species
different from each other in average secondary particle diameter.
In the invention, a metal oxidizing agent, a metal anticorrosive
agent, an organic solvent, and/or a polymer having a weight-average
molecular weight of 500 or more may be added thereto if
necessary.
[0039] The abrasive grains used in the metal polishing slurry of
the invention is, for example, inorganic abrasive grains made of
silica, alumina, zirconia, ceria, titania, germania, silicon
carbide or the like, or organic abrasive grains made of
polystyrene, acrylic polymer, polyvinyl chloride or the like. Of
these materials, preferred are silica, alumina, zirconia, ceria,
titania and germania. More preferred is silica or alumina, and
particularly preferred is colloidal silica or colloidal
alumina.
[0040] Abrasive grains having an average secondary particle
diameter being the range of 1 to 1000 nm are preferred, abrasive
grains having an average secondary particle diameter being the
range of 3 to 300 nm are more preferred, colloidal silica or
colloidal alumina having an average secondary particle diameter
being the range of 1 to 1000 nm are even more preferably preferred,
and colloidal silica or colloidal alumina having an average
secondary particle diameter being the range of 3 to 300 nm are
particularly preferred since good dispersive stability in the metal
polishing slurry is obtained and the generation number of scratches
generated therewith in CMP is small.
[0041] The invention is characterized by containing two or more
abrasive grain species different from each other in average
secondary particle diameter of the abrasive grains, thereby making
it possible to improve the polishing rate of an interlayer
dielectric layer. A preferred example of the abrasive grains
containing two or more abrasive grain species different from each
other in average secondary particle diameter is grains containing
first abrasive grains having an average secondary particle diameter
being in the range of 5 to 39 nm, and second abrasive grains having
an average secondary particle diameter being in the range of 40 to
300 nm. A more preferred example thereof is grains containing first
abrasive grains having an average secondary particle diameter being
in the range of 10 to 39 nm, and second abrasive grains having an
average secondary particle diameter being in the range of 40 to 150
nm. An even more preferred example thereof is grains containing
first abrasive grains having an average secondary particle diameter
being in the range of 12 to 39 nm, and second abrasive grains
having an average secondary particle diameter being in the range of
40 to 90 nm. In a preferred embodiment of the abrasive grains,
three or more abrasive grain species different from each other in
average secondary particle diameter are contained as well as two or
more grain species different from each other therein are contained.
In this case, the abrasive grain species with the average secondary
particle diameters of which are successively arranged from the
smallest value toward the largest value, are defined as first
abrasive grains, second abrasive grains, third abrasive grains, . .
. . When the third abrasive grains and so on are also added, the
average secondary particle diameter of each of the grain species
and the average secondary particle diameter of the whole of the
abrasive grains are each preferably in the range of 1 to 1000 nm.
By combining two or more abrasive grain species each having an
average secondary particle diameter in that range, the abrasive
grains turn into a closest packing state when the abrasive grains
contact a surface to be polished in polishing. Thus, the polishing
rate of an interlayer dielectric layer can be made better and
further the generation of scratches can be prevented. The two or
more abrasive grain species different from each other in average
secondary particle diameter may be a combination of the same kind
of abrasive grains or different kinds of abrasive grains.
[0042] In the case of using two abrasive grain species different
from each other in average secondary particle diameter, a
sufficiently polishing rate for an interlayer dielectric layer may
not be obtained if the average secondary particle diameter of the
first abrasive grains is 5 nm or less. If the second abrasive
grains having an average secondary particle diameter is in the
range of 300 nm or more, the dispersibility may deteriorate and
scratches may be generated. From this viewpoint, the largest value
of the average secondary particle diameter of the second abrasive
grains is preferably 150 nm or less, more preferably 90 nm or
less.
[0043] The abrasive grains used in the invention are abrasive
grains containing abrasive two or more grain species different from
each other in average secondary particle diameter. It is preferred
that the content by percentage of the second abrasive grains, which
have a larger average secondary particle diameter, is larger. For
example, preferred are abrasive grains containing 1 to 50% by mass
of first abrasive grains having an average secondary particle
diameter being in the range of 5 to 39 nm and 50 to 99% by mass of
second abrasive grains having an average secondary particle
diameter being in the range of 40 to 300 nm to whole abrasive
grains. If the content by percentage of the first abrasive grains,
which has an average secondary particle diameter being in the range
of 5 to 39 nm, is less than 1% by mass, the polishing rate of a
blanket substrate on which an organic silicate glass or silicon
dioxide that is used as an interlayer dielectric layer is formed,
tends to be small. If the content by percentage is more than 50% by
mass, the polishing rate of a blanket substrate on which a
silicon-coating film or organic polymer film that is used as an
interlayer dielectric layer is formed, also tends to be small.
[0044] When three or more abrasive grain species different from
each other in average secondary particle diameter are contained, it
is preferred that large abrasive grains which have an average
secondary particle diameter being in the range of 1 to 1000 nm are
contained in a larger amount since the Mechanical effect becomes
large so that the polishing rate becomes large.
[0045] In the invention, the average primary particle diameter of
the abrasive grains is preferably in the range of 2 to 100 nm, more
preferably in the range of 5 to 40 nm, even more preferably in the
range of 2 to 39 nm. If the average primary particle diameter of
the abrasive grains is less than 2 nm, the polishing rate of an
interlayer dielectric layer tends to be declined. On the other
hand, if the average primary particle diameter of the abrasive
grains is more than 100 nm, scratches tends to increase.
[0046] The method for measuring the average secondary particle
diameter is not particularly limited, and may be any existing
average-secondary-particle-diameter measuring method. The diameter
can be measured with, in particular, a submicron particle analyzer
based on the dynamic scattering method. The method for measuring
the average primary particle diameter is not particularly limited,
and may be any existing average-primary-particle-diameter measuring
method. The method is, for example, a method of making an actual
measurement in a TEM or SEM photograph, and may be a method of
measuring the BET specific surface area, and then converting it
into the diameter (the specific surface area converting
method).
[0047] In the invention, the "average secondary particle diameter"
is the average particle diameter of a material made of secondary
particles formed by the aggregation of primary particles. The
"average primary particle diameter" is the average particle
diameter of primary particles.
[0048] Colloidal silica, which is preferred as the abrasive grains,
may be yielded by a known production process based on the
hydrolysis of a silicon alkoxide or ion exchange of sodium
silicate. Colloidal silica yielded by the production process based
on the hydrolysis of a silicon alkoxide is most preferably used
from the viewpoint of particle diameter controllability and alkali
metal impurities. The silicon alkoxide may be generally TEMS
(tetramethoxysilane) or TEOS (tetraethoxysilane). In a method of
hydrolyzing the alkoxide in an alcohol solvent, examples of
parameters which affect the particle diameter include the
concentration of the silicon alkoxide, the concentration of ammonia
used as a catalyst, and the pH, the reaction temperature, the kind
(molecular weight) of the alcohol solvent, and the reaction time.
By adjusting these parameters, a colloidal silica dispersed slurry
having a desired particle diameter and aggregation degree can be
obtained. Colloidal alumina may be yielded by a known production
process based on the hydrolysis of aluminum nitrate.
[0049] The metal-oxide-dissolving agent used in the invention is
not particularly limited, and examples thereof include organic
acids such as formic acid, acetic acid, propionic acid, butyric
acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid,
3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic
acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid,
2-ethylhaxanoic acid, benzoic acid, glycolic acid, salicylic acid,
glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric
acid, adipic acid, pimelic acid, malic acid, phthalic acid, malic
acid, tartaric acid, and citric acid; and organic-acid esters
thereof. Particularly preferred is a metal-oxide-dissolving agent
containing no amino group. If a metal-oxide-dissolving agent
contains an amino group, the pH may turn into a neutral range, so
that the possibility that the pH is not easily adjusted into a low
value is high. If the pH is in a neutral range, a sufficient
polishing rate of a metal or metals (a metal barrier layer and/or
an electroconductive material layer) may not be obtained. The
metal-oxide-dissolving agent used in the invention may be an
ammonium salt of any one of the organic acids, and may be an
inorganic acid such as hydrochloric acid, sulfuric acid or nitric
acid, any ammonium salts of the inorganic acids, such as ammonium
persulfate, ammonium nitrate or ammonium chloride, or chromic acid.
Of these agents, preferred are organic acids such as formic acid,
malonic acid, malic acid, tartaric acid and citric acid since a
practical CMP rate is maintained while the etching rate can be
effectively restrained. These organic acids are more preferably
used for an electroconductive material layer containing at least
one selected from copper, copper alloys, copper oxides, and copper
alloy oxides. These may be used alone or in the form of a mixture
of two or more thereof.
[0050] The pH of the metal polishing slurry of the invention is not
particularly limited, and is preferably in the range of 2 to 5,
more preferably in the range of 2 to 4. If the pH is less than 2,
the corrosion of a metal in an electroconductive material layer may
advance so that the wiring resistance may deteriorate. If the pH is
more than 5, the polishing rate of an electroconductive material
layer may not be sufficiently obtained.
[0051] The metal polishing slurry of the invention may contain a
metal oxidizing agent. The metal oxidizing agent is not
particularly limited, and examples thereof include hydrogen
peroxide (H.sub.2O.sub.2), nitric acid, potassium periodate,
hypochlorous acid, and ozone water. Of these agents, particularly
preferred is hydrogen peroxide. These may be used alone or in the
form of a mixture of two or more thereof.
[0052] When a substrate to which the metal polishing slurry of the
invention is applied is a silicon substrate containing integrated
circuit elements, it is undesired that the substrate is
contaminated with an alkali metal, an alkaline earth metal, a
halide or the like. Therefore, the oxidizing agent is desirably an
oxidizing agent containing no nonvolatile component. However, ozone
water is heavily changed in composition with the passage of time;
thus, hydrogen peroxide is most preferred. However, when the
substrate to which the slurry is applied is a glass substrate
containing no semiconductor element, or the like, an oxidizing
agent containing a nonvolatile component may be used.
[0053] The metal polishing slurry of the invention may contain a
metal anticorrosive agent. The metal anticorrosive agent is not
particularly limited, and is, for example, a compound having a
triazole skeleton, a compound having a pyrazole skeleton, a
compound having a pyrimidine skeleton, a compound having an
imidazole skeleton, a compound having a guanidine skeleton, a
compound having a thiazole skeleton, or the like.
[0054] Examples of the compound having a triazole skeleton include
1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole,
benzotriazole, 1-hydroxybenzotriazole,
1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole,
4-hydroxybenzotriazole, 4-carboxyl(-1H-)benzotriazole,
4-carboxyl(-1H-)benzotriazole methyl ester,
4-carboxyl(-1H-)benzotriazole butyl ester,
4-carboxyl(-1H-)benzotriazole octyl ester, 5-hexylbenzotriazole,
[1,2,3-benzo]triazolyl-1-methyl][1,2,4-triazolyl-1-methyl][2-ethylhexyl]a-
mine, tolyltriazole, naphthotriazole,
bis[(1-benzotriazolyl)methyl]phosphonic acid, and the like.
[0055] Examples of the compound having a pyrazole skeleton include
3,5-dimethylpyrazole, 3-methyl-5-pyrazolone,
3-amino-5-methylpyrazole, 3-amino-5-hydroxypyrazole,
3-amino-5-methylpyrazole, and the like.
[0056] Examples of the compound having a pyrimidine skeleton
include pyrimidine,1,2,4-triazolo[1,5-a]pyrimidine,
1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine,
1,3-diphenyl-pyrimidine-2,4,6-trione, 1,4,5,6-tetrahydropyrimidine,
2,4,5,6-tetraaminopyrimidine sulfate, 2,4,5-trihydropyrimidine,
2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine,
2,4,6-trimethoxypyrimidine, 2,4,6-triphenylpyrimidine,
2,4-diamino-6-hydroxylpyrimidine, 2,4-diaminopyrimidine,
2-acetoamidepyrimidine, 2-aminopyrimidine,
2-methyl-5,7-diphenyl-(1,2,4)triazolo(1,5-a)pyrimidine,
2-methylsulfanylyl-5,7-diphenyl-(1,2,4)triazolo(1,5-a)pyrimidine,
2-methylsulfanylyl-5,7-diphenyl-4,7-dihydro-(1,2,4)triazolo(1,5-a)pyrimid-
ine, 4-aminopyrazolo[3,4-d]pyrimidine, and the like.
[0057] Examples of the compound having an imidazole skeleton
include imidazole, 2-methylimidazole, 2-ethylimidazole,
2-isopropylimidazole, 2-propylimidazole, 2-butylimidazole,
4-methylimidazole, 2,4-dimethylimidazole,
2-ethyl-4-methylimidazole, 2-aminoimidazole,
mercaptobenzoimidazole, and the like.
[0058] Examples of the compound having a guanidine skeleton include
1,3-diphenylguanidine, 1-methyl-3-nitroguanidine, and the like.
[0059] Examples of the compound having a thiazole skeleton include
2-aminothiazole, 4,5-dimethylthiazole, 2-amino-2-thiazoline,
2,4-dimethylthiazole, 2-amino-4-methylthiazole, and the like.
[0060] Of these compounds, the compound having a triazole skeleton
is preferred, and benzotriazole is particularly preferred. These
metal anticorrosive agents may be used alone or in the form of a
mixture of two or more thereof.
[0061] The metal polishing slurry of the invention may contain an
organic solvent. The organic solvent is not particularly limited,
and examples thereof include carbonate compounds such as ethylene
carbonate, propylene carbonate, dimethyl carbonate, diethyl
carbonate, and methylethyl carbonate; lactone compounds such as
butyrolactone and propiolactone; glycol compounds such as ethylene
glycol, propylene glycol, diethylene glycol, dipropylene glycol,
triethylene glycol, and tripropylene glycol; glycol ether compounds
such as ethylene glycol monomethyl ether, propylene glycol
monomethyl ether, diethylene glycol monomethyl ether, dipropylene
glycol monomethyl ether, triethylene glycol monomethyl ether,
tripropylene glycol monomethyl ether, ethylene glycol monoethyl
ether, propylene glycol monoethyl ether, diethylene glycol
monoethyl ether, dipropylene glycol monoethyl ether, triethylene
glycol monoethyl ether, tripropylene glycol monoethyl ether,
ethylene glycol monopropyl ether, propylene glycol monopropyl
ether, diethylene glycol monopropyl ether, dipropylene glycol
monopropyl ether, triethylene glycol monopropyl ether, tripropylene
glycol monopropyl ether, ethylene glycol monobutyl ether, propylene
glycol monobutyl ether, diethylene glycol monobutyl ether,
dipropylene glycol monobutyl ether, triethylene glycol monobutyl
ether, tripropylene glycol monobutyl ether, ethylene glycol
dimethyl ether, propylene glycol dimethyl ether, diethylene glycol
dimethyl ether, dipropylene glycol dimethyl ether, triethylene
glycol dimethyl ether, tripropylene glycol dimethyl ether, ethylene
glycol diethyl ether, propylene glycol diethyl ether, diethylene
glycol diethyl ether, dipropylene glycol diethyl ether, triethylene
glycol diethyl ether, tripropylene glycol diethyl ether, ethylene
glycol dipropyl ether, propylene glycol dipropyl ether, diethylene
glycol dipropyl ether, dipropylene glycol dipropyl ether,
triethylene glycol dipropyl ether, tripropylene glycol dipropyl
ether, ethylene glycol dibutyl ether, propylene glycol dibutyl
ether, diethylene glycol dibutyl ether, dipropylene glycol dibutyl
ether, triethylene glycol dibutyl ether, tripropylene glycol
dibutyl ether, tetrahydrofuran, dioxane, dimethoxyethane,
polyethylene oxide, ethylene glycol monomethyl acetate, diethylene
glycol monoethyl ether acetate, and propylene glycol monomethyl
ether acetate; alcohol compounds such as methanol, ethanol,
propanol, n-butanol, n-pentanol, n-hexanol, and isopropanol; ketone
compounds such as acetone, and methyl ethyl ketone; and other
solvents such as phenol, dimethylformamide, n-methylpyrrolidone,
ethyl acetate, ethyl lactate, and sulfolane.
[0062] The metal polishing slurry of the invention may contain a
polymer having a weight-average molecular weight of 500 or more.
The weight-average molecular weight is more preferably 1500 or
more, in particular preferably 5000 or more. The upper limit of the
weight-average molecular weight is not particularly limited, and is
5000000 or less from the viewpoint of solubility. If the
weight-average molecular weight is less than 500, an excessively
high metal-protecting effect is produced so that a high polishing
rate for a metal barrier layer tends not to be expressed. In the
invention, it is preferred to use at least one water-soluble
polymer having a weight-average molecular weight of 500 or more.
The polymer, which has a weight-average molecular weight of 500 or
more, is not particularly limited, and examples thereof include
polysaccharides such as alginic acid, pectic acid,
carboxymethylcellulose, agar, curdlan, and pullulan; polycarboxylic
acids and salts thereof, such as polyaspartic acid, polyglutamic
acid, polylysine, polymalic acid, polymethacrylic acid, ammonium
polymethacrylate, sodium polymethacrylate, polyamic acid,
polymaleic acid, polyitaconic acid, polyfumaric acid,
poly(p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide,
aminopolyacrylamide, ammonium polyacrylate, sodium polyacrylate,
polyamic acid, a polyamic acid ammonium salt, a polyamic acid
sodium salt, and polyglyoxylic acid; and vinyl polymers such as
polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrolein. These
may be used alone or in the form of a mixture of two or more
thereof.
[0063] However, when a substrate to which the metal polishing
slurry of the invention is applied is a silicon substrate for
semiconductor integrated circuits, or the like, it is undesired
that the substrate is contaminated with an alkali metal, an
alkaline earth metal, a halide or the like. Therefore, the polymer
is preferably a polymer which neither contains an alkali metal, an
alkaline earth metal nor a halide. The polymer is in particular
preferably pectic acid, agar, polymalic acid, polymethacrylic acid,
polyacrylic acid, ammonium polyacrylate, polyacrylamide, polyvinyl
alcohol or polyvinyl pyrrolidone; any ester or ammonium salt
thereof; or the like. However, when the substrate is a glass
substrate or the like, the matter is not applicable.
[0064] The weight-average molecular weight of the polymer can be
measured by use of a calibration curve of standard polystyrene
according to gel permeation chromatography.
[0065] The blend amount of the abrasive grains used in the
invention is preferably from 0.001 to 50 parts by mass, more
preferably from 0.01 to 45 parts by mass, in particular preferably
from 0.1 to 40 parts by mass for 100 parts by mass of the abrasive
grains, the metal-oxide-dissolving agent, and water. If the blend
amount of the abrasive grains is less than 0.001 part by mass, the
polishing rate of a blanket substrate on which a silicon-coating
film or organic polymer used as an interlayer dielectric layer is
formed tends to be small. If the blend amount of the abrasive
grains is more than 50 parts by mass, many scratches tends to be
generated.
[0066] The blend amount of the metal-oxide-dissolving agent used in
the invention is preferably from 0.001 to 20 parts by mass, more
preferably from 0.002 to 15 parts by mass, in particular preferably
from 0.005 to 15 parts by mass for 100 parts by mass of the
abrasive grains, the metal-oxide-dissolving agent, and water. If
the blend amount of the metal-oxide-dissolving agent is less than
0.001 part by mass, the polishing rate of an electroconductive
material layer tends to be declined. If the blend amount is more
than 20 parts by mass, etching is not easily restrained so that the
polished surface tends to become rough.
[0067] The blend amount of the metal oxidizing agent used in the
invention is preferably from 0 to 50 parts by mass, more preferably
from 0.001 to 45 parts by mass, in particular preferably from 0.002
to 40 parts by mass for 100 parts by mass of the abrasive grains,
the metal-oxide-dissolving agent, and water. If the blend amount of
the metal oxidizing agent is more than 50 parts by mass, the
polished surface tends to become rough.
[0068] The blend amount of the metal anticorrosive agent used in
the invention is preferably from 0 to 10 parts by mass, more
preferably from 0.001 to 8 parts by mass, in particular preferably
from 0.002 to 5 parts by mass for 100 parts by mass of the abrasive
grains, the metal-oxide-dissolving agent, and water. If the blend
amount of the metal anticorrosive agent is more than 10 parts by
mass, the polishing rate of an electroconductive material layer
tends to be declined.
[0069] The blend amount of the organic solvent used in the
invention is preferably from 0 to 95 parts by mass, more preferably
from 0.2 to 60 parts by mass, in particular preferably from 0.5 to
50 parts by mass for 100 parts by mass of the abrasive grains, the
metal-oxide-dissolving agent, and water. If the blend amount of the
organic solvent is more than 80 parts by mass, the probability of
ignition is generated. Thus, the amount is not preferred for the
process of the production.
[0070] The blend amount of the polymer used in the invention, which
has a weight-average molecular weight of 500 or more, is preferably
from 0 to 10 parts by mass, more preferably from 0.01 to 8 parts by
mass, in particular preferably from 0.02 to 5 parts by mass for 100
parts by mass of the abrasive grains, the metal-oxide-dissolving
agent, and water. If the blend amount of the polymer is more than
10 parts by mass, the polishing rate of each of an
electroconductive material layer, a metal barrier layer and an
interlayer dielectric layer tends to be declined.
[0071] The metal polishing slurry of the invention may contain a
surfactant, a dye such as Victoria Pure Blue, a pigment such as
phthalocyanine green, or any other colorant as well as the
materials.
[0072] A polishing-receiving film to be polished with the metal
polishing slurry of the invention is a polishing-receiving film
containing two or more selected from an electroconductive material
layer, a metal barrier layer, and an interlayer dielectric layer,
and is, for example, a polishing-receiving film containing an
electroconductive material layer and a metal barrier layer, a
polishing-receiving film containing an electroconductive material
layer and an interlayer dielectric layer, a polishing-receiving
film containing a metal barrier layer and an interlayer dielectric
layer, and a polishing-receiving film containing an
electroconductive material layer, a metal barrier layer, and an
interlayer dielectric layer.
[0073] The metal polishing slurry of the invention is used in the
second CMP polishing step, which is for a patterned substrate after
the first CMP polishing step. Specifically, as illustrated in FIG.
1, the metal polishing slurry of the invention is applied to a
desired pattern substrate (FIG. 1(b) obtained by: preparing a
substrate (FIG. 1(a)) having an interlayer dielectric layer 3
having a surface composed of concave and convex regions, a metal
barrier layer 2 which covers the interlayer dielectric layer 3
along its surface, and an electroconductive material layer 1 which
is filled into the concave regions to cover the metal barrier layer
2; and polishing the electroconductive material layer 1 through the
first CMP polishing step, thereby making the metal barrier layer 2
on the convex regions naked, and causing the electroconductive
material layer 1 in the concave regions to remain. As the polishing
slurry used in the first CMP polishing step, a polishing slurry
usually used in the first CMP polishing step, such as an alumina
based polishing slurry or a silica based polishing slurry may be
used.
[0074] The metal polishing slurry of the invention is used to
polish the metal barrier layer 2 of the patterned substrate in FIG.
1(b), and then continuously polish the interlayer dielectric layer
3, the metal barrier layer 2 and the electroconductive material
layer 1 in such a manner that the patterned substrate (FIG. 1(c1))
having a dishing 4 generated in the electroconductive material 1 is
cancelled, whereby the patterned substrate can be planarized (FIG.
1(c2)). In order to stop the polishing of the interlayer dielectric
layer so as to avoid any dishing, it is advisable to adjust the
polishing rate ratio while adjusting the polishing period
appropriately. About the polishing period, for example, the
polishing rate for a blanket wafer or the like is beforehand
calculated and the period when the interlayer dielectric layer is
polished up to a depth of about 500 to 1000 .ANG. is measured. On
the basis of the period, the polishing period is adjusted.
[0075] Examples of the electroconductive material layer include
copper, any copper alloy, any copper oxide, any copper alloy oxide,
tungsten, any tungsten alloy, silver, and gold. Of these materials,
preferred are copper, any copper alloy, any copper oxide, any
copper alloy oxide, and so on. The electroconductive material layer
may be a film obtained by forming the materials into a film form by
known sputtering or plating.
[0076] The metal barrier layer is formed to prevent the
electroconductive material from diffusing into the interlayer
dielectric layer and improve the adhesion between the interlayer
dielectric layer and the electroconductive material. The
composition of the metal barrier layer is preferably selected from
tungsten, and tungsten compounds such as tungsten nitride and
tungsten alloy; titanium, and titanium compounds such as titanium
nitride and titanium alloy; tantalum, and tantalum compounds such
as tantalum nitride and tantalum alloy; ruthenium, and ruthenium
compounds such ruthenium alloy; alloy made of copper and manganese,
and alloy made of copper, manganese and silicon oxide; and others.
The barrier layer may have a monolayer made of any one of these
materials, or a laminated structure made of two or more
thereof.
[0077] The interlayer dielectric layer is, for example, a
silicon-coating film or an organic polymer film. The
silicon-coating film is, a silica-coating film containing, for
example, silicon dioxide, fluorosilicate glass, organosilicate
glass obtained from trimethylsilane or dimethoxydimethylsilane as a
starting material, silicon oxynitride, hydrogenated silsesquioxane,
silicon carbide, or silicon nitride. The organic polymer film may
be a fully aromatic low-dielectric-constant interlayer dielectric
layer. Of these examples, organic silicate glass is preferred.
[0078] These films may each be formed by CVD, spin coating, dip
coating or spraying. A specific example of the interlayer
dielectric layer is an interlayer dielectric layer in an
LSI-producing process, in particular, in a multilayer
interconnection forming step therein.
[0079] The polishing method of the invention is a method comprising
the step of polishing a polishing-receiving film while supplying
the metal polishing slurry of the present invention onto a
polishing cloth of a polishing table by moving the polishing table
and a substrate having the polishing-receiving film relatively to
each other in the state that the substrate is pushed and pressed
onto the polishing cloth.
[0080] The machine for the polishing may be an ordinary polishing
machine having a holder for holding a substrate, and a table to
which a polishing cloth is attached (and to which a motor giving a
variable rotation speed, and so on are fitted). The polishing cloth
may be an ordinary nonwoven cloth, a foamed polyurethane, a porous
fluorine-contained resin or the like, and is not particularly
limited.
[0081] Conditions for the polishing are not particularly limited,
and the rotational speed of the table is preferably as low as 200
rpm or less so as for the substrate not to be spun out. The pushing
pressure of the substrate having a polishing-receiving film, onto
the polishing cloth is preferably from 1 to 100 kPa. The pressure
is more preferably from 5 to 50 kPa in order that
polishing-rate-evenness in the polishing-receiving plane and
pattern-smoothness can be satisfied. During the polishing, the
metal polishing slurry of the invention is continuously supplied to
the polishing cloth through a pump or the like. The supply amount
thereof is not particularly limited, and is preferably an amount
permitting the polishing cloth surface to be covered with the metal
polishing slurry. After the polishing, it is preferred to wash the
substrate sufficiently with flowing water, use a spin drier or the
like to drop water droplets adhering onto the substrate, and then
dry the substrate.
[0082] A purpose of the invention is to polish the
electroconductive material layer 1 (for example, a copper layer)
illustrated in FIG. 1(a) until the metal barrier layer 2 is made
naked, so as to turn the workpiece into a state illustrated in FIG.
1(b) (first CMP polishing step), and then cancel the resultant
dishing in the next step of polishing the metal barrier layer 2
(second CMP polishing step). As a polishing slurry used in the
first CMP polishing step for polishing the electroconductive
material layer 1, which is to be wiring metal such as copper,
various slurries have been suggested hitherto. In recent years,
polishing slurries for decreasing the amount of dishing have been
suggested; however, it is substantially impossible that dishing is
completely prevented. In other words, as illustrated in FIG. 1(b),
excessive polishing of copper is more or less generated even when
the used polishing slurry is selected from all slurries and
polishing conditions are set into any variation. As a result, the
dishing 4 is unfavorably generated.
[0083] The metal polishing slurry of the invention makes it
possible to improve the dishing in the second CMP polishing step.
The metal polishing slurry of the invention is used to apply the
second CMP polishing step to the patterned substrate in FIG. 1(b),
thereby polishing the metal barrier layer in any region other than
the groove regions so as to yield the patterned substrate having
the dishing 4 generated in the first CMP polishing step (FIG.
1(c1)) once in the polishing process. Subsequently, the patterned
substrate is polished, whereby a patterned substrate as illustrated
in FIG. 1(c2), which has a planarized surface, can be yielded. In
order to polish the patterned substrate into such a state, it is
important to adjust the ratio between the polishing rate of the
electroconductive material layer (copper film) and that of the
interlayer dielectric layer.
[0084] That is, it is important that the polishing rate of the
electroconductive material layer is lower than that of the
interlayer dielectric layer in order to cancel the dishing. About
the ratio to be selected, the ratio of the polishing rate of the
electroconductive material to that of the interlayer dielectric
layer is preferably 0.72 or less, and is in particular preferably
from 0.35 to 0.70.
[0085] In order to adjust the polishing rate of the
electroconductive material layer (for example, a copper film) in
the invention, a method of adjusting the rate in accordance with
the amount of an oxidizing agent (for example, hydrogen peroxide)
is given. Specifically, for example, the polishing rate of the
electroconductive material layer (copper film) becomes larger as
the amount of the oxidizing agent to be added is made larger. In a
more specific example, the removal of the copper film is about 300
.ANG./minute when the amount of a 30% solution of hydrogen peroxide
in water is about 1%. As the amount of the oxidizing agent becomes
larger, the polishing rate of the metal barrier layer also becomes
larger.
[0086] In the meantime, the polishing rate of the interlayer
dielectric layer can be adjusted by adjusting the particle diameter
of the abrasive grains or the blend amount of the abrasive grains.
Specifically, as the particle diameter is larger, the polishing
rate tends to become higher. As the blend amount of the abrasive
grains is larger, the polishing rate tends to become larger. In
order to polish a silicon-coating film or organic polymer film at a
high velocity, preferred is a method of blending an organic solvent
to make the wettability high. In order to restrain the polishing
rate of a silicon-coating film or organic polymer film, effective
is a method of blending no organic solvent or making the blend
amount of an organic solvent small.
[0087] In order for the metal polishing slurry to give/have the
polishing rate ratio and polishing characteristics as described
above out of the structural requirements described above, it is
preferred to satisfy any one of the following requirements: two or
more abrasive grain species different from each other in average
secondary particle diameter are incorporated into a polishing
slurry, and further the pH of the polishing slurry is set into the
range of 2 to 5; the metal-oxide-dissolving agent is appropriately
selected (specifically, preferred is an metal-oxide-dissolving
agent containing no amino group, in particular, formic acid,
malonic acid, malic acid, tartaric acid or citric acid); and the
slurry contains an oxidizing agent. Alternatively, it is more
preferred that two or more abrasive grain species different from
each other in average secondary particle diameter are incorporated
into a polishing slurry, and further two or more of the
requirements are combined with each other.
EXAMPLES
[0088] The invention will be described by way of examples
hereinafter. However, the invention is not limited by these
examples.
Examples 1 to 8, and Comparative Examples 1 to 2
(Polishing Slurry Producing Method)
[0089] Some materials shown in Table 1 were mixed with each other
in individual amounts (parts by mass) to prepare each of metal
polishing slurries used in Examples 1 to 8 and Comparative Examples
1 to 2. The metal polishing slurry was used to polish each of
substrates yielded described below under polishing conditions
described below.
(Method for Measuring the Average Secondary Particle Diameter)
[0090] The average secondary particle diameter of abrasive grains
was measured with a submicro particle analyzer (machine name: N5
Submicron Particle Size Analyzer, manufactured by Beckman Coulter,
Inc.) based on the dynamic scattering method.
(Method for Measuring Average Primary Particle Diameter)
[0091] About the average primary particle diameter of abrasive
grains, an ultra high resolving-power electron microscope (SEM)
(machine name: Hitachi S-4800, manufactured by Hitachi Kyowa
Engineering Co., Ltd.) was used to take a photograph thereof, and
then the size was actually measured.
(Substrates)
[0092] Substrates described below were prepared.
(A) Blanket Substrates:
[0093] Blanket substrates (a1): trimethylsilane was used as a
starting material to form organosilicate glass film (thickness:
1000 nm) on a silicon substrate by CVD.
[0094] Blanket substrates (a2): silicon dioxide of 1000 nm
thickness was formed on a silicon substrate.
[0095] Blanket substrates (a3): tantalum of 200 nm thickness was
formed on a silicon substrate.
[0096] Blanket substrates (a4): copper of 1600 nm thickness was
formed on a silicon substrate.
(B) Patterned Substrates:
[0097] Patterned substrates (b1): trimethylsilane was used as a
starting material to form organosilicate glass film as an
interlayer dielectric layer on a silicon substrate by CVD. A known
method was used to make grooves (concaves) of 0.5 .mu.m depth in
the organosilicate glass. On the surface thereof, a tantalum film
of 200 nm thickness was formed as a metal barrier layer along the
surface by sputtering. A copper film of 1.0 .mu.m thickness was
formed as an electroconductive material layer on the tantalum film
by sputtering, so as to be embedded into the grooves. A silica
based polishing slurry (product name: HS-0500-10, manufactured by
Hitachi Chemical Co., Ltd.) was used to polish only projected
portions of the copper film in a first CMP step to make concave
portions of the barrier layer naked into the polished surface. In
this way, patterned substrates (b1) were each yielded.
[0098] Patterned substrates (b2): the same operations as descried
above were made except that instead of the organosilicate glass,
silicon dioxide was used as the interlayer dielectric layer. In
this way, patterned substrates (b2) were each yielded.
(Polishing Conditions)
[0099] Polishing pad: a foamed polyurethane resin (model number:
IC1000, manufactured by Rodale Co.)
[0100] Polishing pressure: 140 kg/cm.sup.2 (13.73 kPa)
[0101] Rotation speed of the polishing table and the wafer holder:
90 rpm
[0102] Supply amount of each of the polishing slurries: 150
mL/min.
(Evaluation Items)
[0103] (1) Polishing rates: each of the metal polishing slurries
was used to polish the individual blanket substrates (a1) to (a4)
for 60 seconds. The polishing rate of the organosilicate glass and
that of the silicon dioxide were each obtained by measuring the
difference between the film thickness before the polishing and that
after the polishing with a film thickness tester (product name:
RAMDA ACE manufactured by Dainippon Screen Mfg. Co., Ltd. The
polishing rate of the tantalum and that of the copper were each
obtained by calculating the difference between the film thickness
before the polishing and that after the polishing by conversion
from the electric resistance values.
[0104] (2) Flatness (dishing amount): each of the metal polishing
slurries was used to polish the individual patterned substrates
(b1) to (b2) for 90 seconds. A stylus surface profilometer was used
to measure the surface form of a stripe-form pattered region formed
in each of the patterned substrates, wherein wiring metal regions
each having a width of 100 .phi.m and dielectric layer regions each
having a width of 100 .mu.m were alternately arranged. The amount
of the film reduction from interlayer dielectric layer regions to
the wiring metal regions was measured. This was used as an index of
the flatness.
[0105] (3) Flatness (erosion amount): each of the metal polishing
slurries was used to polish the individual patterned substrates
(b1) to (b2) for 90 seconds. The stylus surface profilometer was
used to measure the surface form of a stripe-form pattered region
having a total width of 2.5 mm and formed in each of the patterned
substrates, wherein wiring metal regions each having a width of 4.5
.mu.m and dielectric layer regions each having a width of 0.5 .mu.m
were alternately arranged. The amount of the film reduction of the
interlayer dielectric layer regions near the center of the pattern
to the interlayer dielectric layer regions in the periphery of the
stripe-form patterned region was measured. This was used as an
index of the flatness.
[0106] The metal polishing slurries of Examples 1 to 8 and
Comparative Examples 1 to 2 were used to make the evaluations. The
results are shown in Tables 1 and 2.
TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 Abrasive grains Colloidal
silica A 2 0 0 0 0 Colloidal silica B 0 2 2.5 3 0 Colloidal silica
C 0 0 0 0 2 Colloidal silica D 3 6 0 9 0 Colloidal silica E 0 0 4.5
0 4 Average secondary particle diameter of the 69 70 91 71 90 whole
of abrasive grains Metal-oxide- Malonic acid 0.5 0 0.5 0 0.5
dissolving Malic acid 0 0.5 0 0.5 0 agent Oxidizing Hydrogen
peroxide 1 1 1 1 1 agent Metal Benzotriazole 0.1 0.1 0.1 0.1 0.1
anticorrosive Triazole 0 0 0 0 0 agent Organic Isopropyl alcohol 0
6 0 0 0 solvent Propylene glycol monomethyl eter 5 0 0 5 0
Propylene glycol monopropyl eter 0 0 7 0 0 Polymer Polyacrylic acid
(weight-average molecular 0.05 0 0 0.05 0 weight: 25000) Water 90
90 90 90 90 pH of metal polishing slurry 3 3 3 3 3 Polishing rate
Blanket substrate (a1) 520 590 480 610 410 (.ANG./min.) Blanket
substrate (a2) 610 680 620 750 640 Blanket substrate (a3) 500 480
470 620 610 Blanket substrate (a4) 310 290 320 310 280 Dishing
Patterned substrate (b1) 600 550 610 570 800 amount (.ANG.)
Patterned substrate (b2) 550 500 550 450 540 Erosion Patterned
substrate (b1) 590 560 600 550 800 amount (.ANG.) Patterned
substrate (b2) 540 490 560 440 560
[0107] The particle diameters of the colloidal silicas A to E shown
in Tables 1 and 2 are as follows:
[0108] Colloidal silica A: average secondary particle diameter: 22
nm, and average primary particle diameter: 11 nm
[0109] Colloidal silica B: average secondary particle diameter: 28
nm, and average primary particle diameter: 13 nm
[0110] Colloidal silica C: average secondary particle diameter: 50
nm, and average primary particle diameter: 26 nm
[0111] Colloidal silica D: average secondary particle diameter: 70
nm, and average primary particle diameter: 43 nm
[0112] Colloidal silica E: average secondary particle diameter: 90
nm, and average primary particle diameter: 50 nm
TABLE-US-00002 TABLE 2 Comparative Example Example 6 7 8 1 2
Abrasive grains Colloidal silica A 3 0 0 0 6 Colloidal silica B 0 1
2 0 0 Colloidal silica C 0 5 0 0 0 Colloidal silica D 6 0 6 6 0
Colloidal silica E 0 0 0 0 0 Average secondary particle diameter of
68 50 72 71 22 the whole of abrasive grains Metal-oxide- Malonic
acid 0.5 0 0.5 0.5 0 dissolving Malic acid 0 0.5 0 0 0.5 agent
Oxidizing Hydrogen peroxide 1 1 1 1 1 agent Metal Benzotriazole 0.1
0.1 0.1 0.1 0.1 anticorrosive Triazole 0.1 0 0 0 0 agent Organic
solvent Isopropyl alcohol 0 6 0 0 6 Propylene glycol monomethyl
eter 5 0 0 5 0 Propylene glycol monopropyl eter 0 0 0 0 0 Polymer
Polyacrylic acid (weight-average 0 0.05 0 0.05 0 molecular weight:
25000) Water 90 90 90 100 100 pH of metal polishing slurry 3 3 3 3
3 Polishing rate Blanket substrate (a1) 600 530 420 300 310
(.ANG./min.) Blanket substrate (a2) 690 590 690 410 390 Blanket
substrate (a3) 550 600 570 430 500 Blanket substrate (a4) 310 300
270 310 300 Dishing Patterned substrate (b1) 540 590 750 1050 1200
amount (.ANG.) Patterned substrate (b2) 490 560 520 1050 1050
Erosion amount Patterned substrate (b1) 530 600 780 1100 1190
(.ANG.) Patterned substrate (b2) 510 550 500 1010 1350
[0113] In Comparative Examples 1 and 2, the dishing amount and the
erosion amount are large since the polishing rate thereof is small
for the blanket substrate (a1) or (a2) on which the organosilicate
glass or silicon dioxide, which is an interlayer dielectric layer,
is formed. On the other hand, in Examples 1 to 8, the polishing
rate thereof is large for the blanket substrate (a1) or (a2) on
which the organosilicate glass or silicon dioxide, which is an
interlayer dielectric layer, is formed. Thus, the dishing amount
and the erosion amount are small. It has been understood that a
metal polishing slurry as found out in Examples is excellent in
being made finer and thinner and in dimension precision and in
electric characteristics, is high in reliability, and can attain a
decrease in costs.
INDUSTRIAL APPLICABILITY
[0114] According to the invention, a metal polishing slurry can be
obtained which gives a large polishing rate of an interlayer
dielectric layer, and is high in the flatness of the polished
surface. This metal polishing slurry is suitable for a
semiconductor device which is excellent in being made finer and
thinner and in dimension precision and in electric characteristics,
is high in reliability, and can attain a decrease in costs.
[0115] According to the invention, a metal polishing slurry can be
obtained which can keep the polishing rate of an interlayer
dielectric layer without lowering the polishing rate of a metal
barrier layer, so as to give a high flatness of polished surfaces
and exhibit a good productivity as well as the advantageous effect
of the invention is produced.
[0116] According to the invention, a metal polishing slurry can be
obtained which is excellent in washability after polishing, so as
to give a high flatness of a polished surface and exhibit a good
productivity as well as the advantageous effects of the invention
are produced.
[0117] According to the invention, a metal polishing slurry can be
obtained which makes the polishing rate of a metal barrier layer
and that of an interlayer dielectric layer high, so as to give a
high flatness of polished surfaces and exhibit a good productivity
as well as the advantageous effects of the invention are
produced.
[0118] According to the invention, a metal polishing slurry can be
obtained which causes the generation of scratches to be restrained
as well as the advantageous effects of the invention are
produced.
[0119] According to the invention, a metal polishing slurry can be
obtained which makes it possible to adjust the polishing rate of an
electroconductive material layer made of copper, copper alloy or
the like as well as the advantageous effects of the invention are
produced.
[0120] According to the invention, a metal polishing slurry can be
obtained which makes it possible to adjust the polishing rate of an
electroconductive material layer made of copper, copper alloy or
the like and remove residues of the electroconductive material such
as copper as well as the advantageous effects of the invention are
produced.
[0121] According to the invention, a metal polishing slurry can be
obtained which is excellent in the polish-evenness of an
electroconductive material layer made of copper, copper alloy or
the like, a metal barrier layer and an interlayer dielectric layer
as well as the advantageous effects of the invention are
produced.
[0122] According to the invention, a metal polishing slurry which
has the advantageous effects of the invention can be obtained for
an electroconductive material layer made of copper, copper alloy or
the like.
[0123] According to the invention, a metal polishing slurry which
has the advantageous effects of the invention can be obtained for a
metal barrier layer selected from tantalum, tantalum compounds,
titanium, titanium compounds, tungsten and tungsten compounds.
[0124] According to the invention, a polishing method can be
obtained for the production of a semiconductor device which is
excellent in being made finer and thinner and in dimension
precision and in electric characteristics, is high in reliability,
and can attain a decrease in costs.
* * * * *